Nonresonant microwave absorption in Bi2212 single crystal: Second peak and microwave power dependence

Abstract

Nonresonant microwave absorption (NMA) measurements were carried out at liquid-nitrogen temperature on a high quality Bi2212 single crystal, as a function of microwave power in three mutual orientations of crystal ab plane, dc field (Hdc), and microwave magnetic field (Hw). NMA line shapes in Bi2212 crystal are complicated with a narrow peak (P1 peak) located near zero field, followed by a much broader second peak (P2 peak) in the particular orientations. More excitingly, we show that the P2 peak qualitatively evolves as a function of microwave power in the orientation of Hdc ⊥ ab plane, $$H_W | {ab}.$$ plane, and Hdc ⊥ Hw. In this configuration, as the microwave power is progressively increased, the broad P2 peak first gets smeared off and then a multiple peak structure appears, which develops into another narrower second peak (Ps-peak) at high enough microwave powers. In the orientation of $$H_{dc} | {ab}.$$ plane, Hw ⊥ ab plane, and Hdc ⊥ Hw, we report for the first time the appearance and disappearance of a new second peak (P2-like peak) as a function of microwave power.